Our guest surgeon shows that if you have great skill, you can chop the nucleus with just about any instrument and in this case that is a sharp 25g needle. The sharp tip helps penetrate the dense nucleus, but you have to be careful because if it contacts the posterior capsule it will likely puncture it. If you want to be more cautious, you can use an actual chopper with the phaco probe or you can even split the nucleus using a viscoelastic cannula as shown in this 2018 Cataract Coach video: https://cataractcoach.com/2018/08/05/nucleus-chop-with-a-27g-cannula/